Thin film forming equipment and method

ABSTRACT

A thin film forming equipment and a method for forming thin films are provided which are capable of forming the thin film of high quality and of effectively preventing CVD material gas from leaking to surroundings at a low cost. The thin film equipment contains a substrate, a substrate holding device used to hold the substrate and a device used to provide an atmospheric gas to a surface of the substrate held by the substrate holding device, wherein an upper face of the substrate held by the substrate holding device and an upper face of the substrate holding device are almost on one plane.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a thin film forming equipmentand a thin film forming method used for correcting defects in asubstrate having a plane pattern structure such as a photomask, liquidcrystal substrate or a like.

[0003] 2. Description of the Related Art

[0004] AlaserCVD (Chemical Vapor Deposition) method is disclosed in U.S.Pat. No. 4,801,352 in which a thin film is formed at a local place on asubstrate by radiating a specified gas introduced at the local place onthe substrate with a laser to decompose the substrate.

[0005]FIG. 4 is a cross-sectional view of conventional thin film formingequipment. As depicted in FIG. 4, a gas window 52 is mounted on asubstrate 51. The gas window 52 is so constructed that there is a smallclearance (for example, of 0.5 mm) between an upper face of thesubstrate 51 and a lower face of the gas window 52. The gas window 52 isprovided with a gas retention chamber 53, a gas introducing section 54,a gas exhausting section 55 and a laser window 56. The gas retentionchamber 53 is a chamber for the retention of CVD materials such as gasesof organic metal compounds or a like. The gas introducing section 54 isa section used for introducing the CVD materials into the gas retentionchamber 53. The gas exhausting section 55 is composed of ring-shapedtrenches 55 a formed in the circumference of the gas retention chamber53 and of an exhausting section 55 c connected through a hole 55 b,which is used for exhausting the gas discharged from the gas retentionchamber 53. The laser window 56 is used for radiating the CVD materialsstaying in the gas retention chamber 53 with the laser to decomposethem.

[0006] The substrate 51 is held by the holder 57. That is, the substrate51 is held by hanging an end portion of the substrate 51 on a stepsection 57 a of the holder 57. A transmitting illuminating source 58 isused to check a quality of films formed by the CVD process. A lens 59 isused for collecting laser light. A flow of gases used as the CVDmaterials is shown by arrow marks in FIG. 4.

[0007] However, following problems arise when the gas retention chamber53 of the above equipment is positioned in the proximity of the endportion of the substrate 51 and the thin film is formed in the proximityof the end portion of the substrate 51. Since there is a step areabetween the upper face of the substrate 51 and the upper face of theholder 57, if the gas retention chamber 53 is positioned in theproximity of the end portion of the substrate 51, the gas is suctionedfrom the exhausting section 55 c through the ring-shaped trench 55 a andthe gas exhausted from the gas retention chamber 53 is to be ejected,air currents are influenced at the step area and the air flows into thegas retention chamber 53 as shown by the arrow “a” in some cases,causing degradation in the quality of the film formed by the CVDprocess.

[0008] Also, there are some cases in which gases used as the CVDmaterials are not completely ejected through the trench 55 a from theexhausting section 55 c. In some cases, gases used as the CVD materialsleak to surroundings.

SUMMARY OF THE INVENTION

[0009] In view of the above, it is an object of the present invention toprovide a thin film forming equipment and a method for forming thinfilms which are capable of forming the thin film of high quality and ofeffectively preventing gases used as CVD materials or a like fromleaking to surroundings at a low cost.

[0010] According to a first aspect of the present invention, there isprovided a thin film forming equipment including:

[0011] a substrate;

[0012] a substrate holding device used to hold the substrate;

[0013] a device used to provide atmospheric gas to a surface of thesubstrate held by the substrate holding device; and

[0014] whereby an upper face of the substrate held by the substrateholding device and an upper face of the substrate holding device arealmost on one plane.

[0015] In the foregoing, a preferable mode is one wherein the substrateholding device has a cover body which is disposed in an area surroundingthe substrate held by the substrate holding device and wherein an upperface of the cover body and the upper face of the substrate are almost onone plane.

[0016] Also, a preferable mode is one wherein the substrate holdingdevice is provided with a trench along a circumference of the heldsubstrate and the atmospheric gas is able to be ejected through thetrench.

[0017] Also, a preferable mode is one wherein a sheet is provided at aboundary between the held substrate and the substrate holding device.

[0018] Furthermore, a preferable mode is one wherein the thin filmforming equipment provides the atmospheric gas to a surface of thesubstrate held by the substrate holding device and forms the thin filmon the substrate by decomposing the atmospheric gas and wherein the thinfilm forming equipment further includes gas introducing means forintroducing the atmospheric gas, a gas retention chamber for retentionof the introduced gas using the gas introducing means, gas dischargingmeans for discharging gas ejected from the gas retention means and laserradiating means for decomposing gas staying at the gas retention chamberby laser irradiation.

[0019] According to a second aspect of the present invention, there isprovided a method for forming a thin film on a substrate by decomposinggas introduced to a surface of a substrate held by a substrate holdingdevice including a step of preventing the gas introduced to the surfaceof the substrate from being influenced by outside air.

[0020] According to a third aspect of the present invention, there isprovided a method for forming a thin film on a substrate by introducinggas to a surface of a substrate held by a substrate holding device, byradiating the introduced gas with laser, by decomposing the introducedgas and then by suctioning and discharging decompositional by-products,including a step of preventing the gas introduced to the surface of thesubstrate from being influenced by outside air.

[0021] In the foregoing, it is preferable that the upper face of thesubstrate and the upper face of the substrate holding device are almoston one plane to prevent gas introduced on the substrate surface frombeing influenced by outside gas.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, advantages and features of thepresent invention will be more apparent from the following descriptiontaken in conjunction with the accompanying drawings in which:

[0023]FIG. 1 is a cross-sectional view of thin film forming equipmentaccording to a first embodiment of the present invention;

[0024]FIG. 2 is a cross-sectional view of thin film forming equipmentaccording to a second embodiment of the present invention;

[0025]FIG. 3 is a perspective view of the thin film forming equipmentaccording to the second embodiment; and

[0026]FIG. 4 is a cross-sectional view of conventional thin film formingequipment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Best modes of carrying out the present invention will bedescribed in further detail using various embodiments with reference tothe accompanying drawings.

First Embodiment

[0028]FIG. 1 is a cross-sectional view of thin film forming equipmentaccording to a first embodiment of the present invention. As shown inFIG. 1, the gas window 2 is so displaced that there is a small clearance(0.5 mm) between an upper face of the substrate 1 and a lower face ofthe gas window 2.

[0029] The gas window 2 is comprised of a gas retention chamber 3, a gasexhausting section 5 (including an exhausting section 5 c communicatingwith trench 5 a and trench 5 b through a hole 5 b) and a laser window 6.The gas retention chamber 3 is a chamber for the retention of CVD(Chemical Vapor Deposition) materials such as gases of organic metalcompounds or a like. The gas introducing section 4 is used forintroducing the CVD materials into the gas retention chamber 3. The gasexhausting section 5 is used for exhausting gases discharged from thegas retention chamber 3. The laser window 6 is used for radiating theCVD materials staying in the gas retention chamber 3 with the laser todecompose them.

[0030] The substrate 1 is held by the holder 7. That is, the substrate 1is held by hanging an end portion of the substrate 1 on a step portion 7a of a holder 7. A transmitting illuminating source 8 is used to check aquality of a film formed by the CVD process. A lens 9 is for collectinglaser light. Configurations of the equipment shown in FIG. 1 differgreatly from those of the equipment in FIG. 4 in that the former(PresentEmbodiment) has a cover while the latter (Prior Art) does not. As shownin FIG. 1, according to the first embodiment, the equipment is providedwith the cover 10 in a manner that it covers an upper face of the holder7 surrounding the substrate 1. This allows an upper face of thesubstrate and an upper face of the cover 10 on the holder 7 to be on oneplane.

[0031] An end portion 10 a of the cover 10 disposed opposite to thesubstrate 1 is formed in a tapered form. This can prevent the cover 10from contacting with one end of the substrate 1 at a time of opening andclosing of the cover 10. According to the present embodiment, even ifthe thin film is formed by the same CVD method as in the prior art shownin FIG. 4, the flow-in of air does not occur, unlike in the case of theprior art in FIG. 4 in which the flow-in of air is shown by an arrow“a”. That is, during a formation of the thin film, since outside air(i.e., oxygen) does not flow into the gas retention chamber 3, gasesused as the CVD materials introduced into the gas retention chamber 3are not influenced by the outside air. Therefore, the thin film of ahigh quality can be formed by the CVD process. Also, gases used as theCVD materials do not leak to the surroundings. Since these effects canbe obtained simply by providing the cover 10, the first embodiment ofthe present invention can be carried out very simply and at a low cost.The material for the CVD, i.e., Cr (CO)₆ is introduced by a carrier gas(Ar gas with a flow-rate of 200 sccm (standard cubic centimeter perminute)) into the gas retention chamber 3 in a manner that a pressure ofCr(CO)₆ is at 0.3 Torr. A discharging flow-rate at the gas exhaustingsection is set to 600 sccm. The Cr thin film is then formed in proximityto the end portion of the substrate by laser radiation and the CVDprocess.

[0032] In the conventional equipment (10 as shown in FIG. 4) not havingthe cover, a transparent film having no light-interceptivecharacteristic is formed at a position being by 10 mm inside from theend portion of the substrate 51. The resulting film shows that oxygen(air) has entered into the gas retention chamber 53. That is, due to theflow-in of oxygen into the gas retention chamber 53, the film formed bythe CVD process is not metal chromium, but chromium oxide, resulting inthe formation of the transparent film described above. The analysis of aconcentration of Cr by collecting the gas flowing around the gas window52 has revealed that the concentration of Cr exceeds 1 ppm (whenconverted to gas concentration) . This shows that the gas Cr (CO)₆ hasleaked to the surroundings.

[0033] In contrast, in the equipment provided with the cover 10according to the first embodiment as shown in FIG. 1, a desiredlight-interceptive Cr film is formed even at the end portion of thesubstrate 1. This shows that no oxygen (air) has flowed into the gasretention chamber 3 and the film formed by the CVD process is metalchromium. The analysis of the concentration of Cr by collecting the gasflowing around the gas window 52 has revealed that the concentration ofCr is not more than 0.05 ppm (within the limit of measurement) . Thisshows that the gas Cr(CO)₆ has not leaked to the surroundings.

[0034] As described above, unlike in the case of the prior art shown inFIG. 4, according to the present embodiment, by providing the cover 10,the step section 7 a can be removed. However, if the depth of a stepsection 7 a of the holder 7 is equal to a thickness of the substrate 1,the step can also be removed without the cover 10. There is, however,problem in that it is difficult to take the substrate 1 from the holder7 easily.

Second Embodiment

[0035]FIG. 2 is a cross-sectional view of thin film forming equipmentaccording to a second embodiment of the present invention. FIG. 3 is aperspective view of the thin film forming equipment according to thesecond embodiment.

[0036] In the thin film forming equipment according to the secondembodiment, a holder 7 is provided with trenches 11 along thecircumference (on 4 sides) of the substrate 1 and these trenches 11 arecommunicating with discharging ports 12. The cover 10 is of a type ofrotational movement opening and closing with hinges 13. Configurationsof the thin film forming equipment of the second embodiment are the sameas those of the first embodiment except those described above and thesame reference numbers in the second embodiment designate correspondingparts in the first embodiment. Detailed description of the sameconfiguration is omitted accordingly.

[0037] In the thin film forming equipment according to the secondembodiment, by providing the holder 7 with the trenches 11 and thedischarging port 12, the leak of the CVD materials to the surroundingscan be more completely prevented. Moreover, even if the clearancebetween the substrate 1 and the cover 10 becomes larger somewhat, theleak of the CVD materials can be avoided and the degradation in qualityof the film to be formed is small. For example, in the first embodiment,the clearance between the substrate 1 and the cover 10 is set to be 0.1mm. However, in the second embodiment, even if the clearance is set to0.3 mm, the leak of the CVD materials and the degradation of the filmquality can be successfully prevented. This means that high accuracy inattaching the cover 10 is not required so much, making easy the mountingof the cover 10. Furthermore, since the clearance between the substrate1 and the cover 10 can be somewhat larger, the damage to the substrateat a time of opening and closing can be minimized.

[0038] Also, according to the second embodiment, a sheet 14 (forexample, a Teflon sheet with thickness of 30 μm) is provided along anaperture of the cover 10 (as shown by dashed lines in FIG. 3). When thecover 10 is closed at the substrate 1 disposed on the holder 7, since anend of the sheet 14 is positioned fitly along an end portion of thesubstrate 1, even if the clearance between the substrate 1 and the cover10 is somewhat wide, neither the leak of the CVD material gas nordegradation of the film to be formed occurs. Therefore, the clearance of0.5 mm between the substrate 1 and the cover 10 is possible to achievethe above purposes.

[0039] As described above, according to the present invention, the thinfilm of high quality can be formed and the leak of the CVD material gasto the surroundings can be prevented at a low cost.

[0040] It is apparent thus that the present invention is not limited tothe above embodiments but may be changed and modified without departingfrom the scope and spirit of the invention.

[0041] Finally, the present application claims the priority of JapanesePatent Application No. Hei11-080506 filed on Mar. 24, 1999, which isherein incorporated by reference.

What is claimed is:
 1. A thin film forming equipment comprising: asubstrate; a substrate holding device used to hold said substrate; adevice used to provide an atmospheric gas to a surface of said substrateheld by said substrate holding device; and whereby an upper face of saidsubstrate held by said substrate holding device and an upper face ofsaid substrate holding device are almost on one plane.
 2. The thin filmforming equipment according to claim 1, wherein said substrate holdingdevice is provided with a trench along a circumference of said heldsubstrate and said atmospheric gas is able to be discharged through saidtrench.
 3. The thin film forming equipment according to claim 1, whereina sheet is provided at a boundary between said held substrate and saidsubstrate holding device.
 4. The thin film forming equipment accordingto claim 1, wherein said thin film forming equipment provides saidatmospheric gas to the surface of said substrate held by said substrateholding device and forms said thin film on said substrate by decomposingsaid atmospheric gas; and wherein: said thin film forming equipmentfurther comprises gas introducing means for introducing said atmosphericgas, a gas retention chamber for retention of said introduced gas usingsaid gas introducing means, gas discharging means for discharging gasejected from said gas retention means and laser radiating means fordecomposing gas staying at said gas retention chamber by laserirradiation.
 5. A thin film forming equipment comprising: a substrate; asubstrate holding device used to hold said substrate; a device used toprovide an atmospheric gas to a surface of said substrate held by saidsubstrate holding device; whereby an upper face of said substrate heldby said substrate holding device and an upper face of said substrateholding device are almost on one plane; and wherein said substrateholding device has a cover body which is disposed in an area surroundingsaid substrate held by said substrate holding device and wherein anupper face of said cover body and the upper face of said substrate arealmost on one plane.
 6. The thin film forming equipment according toclaim 5, wherein said substrate holding device is provided with a trenchalong a circumference of said held substrate and said atmospheric gas isable to be discharged through said trench.
 7. The thin film formingequipment according to claim 5, wherein a sheet is provided at aboundary between said held substrate and said substrate holding device.8. The thin film forming equipment according to claim 5, wherein saidthin film forming equipment provides said atmospheric gas to the surfaceof said substrate held by said substrate holding device and forms saidthin film on said substrate by decomposing said atmospheric gas; andwherein: said thin film forming equipment further comprises gasintroducing means for introducing said atmospheric gas, a gas retentionchamber for retention of said introduced gas using said gas introducingmeans, gas discharging means for discharging gas ejected from said gasretention means and laser radiating means for decomposing gas staying atsaid gas retention chamber by laser irradiation.
 9. A method for forminga thin film on a substrate by decomposing gas introduced to a surface ofa substrate held by a substrate holding device comprising a step ofpreventing said gas introduced to said surface of said substrate frombeing influenced by outside air.
 10. The method for forming the thinfilm according to claim 9, wherein an upper face of said substrate andan upper face of said substrate holding device are almost on one planeto prevent gas introduced on said substrate surface from beinginfluenced by outside gas.
 11. A method for forming a thin film on asubstrate by introducing gas to a surface of a substrate held by asubstrate holding device, by radiating said introduced gas with laser,by decomposing said introduced gas and then by suctioning anddischarging decompositional by-products, comprising a step of preventingsaid gas introduced to said surface of said substrate from beinginfluenced by outside air.
 12. The method for forming the thin filmaccording to claim 11, wherein an upper face of said substrate and anupper face of said substrate holding device are almost on one plane toprevent gas introduced on said substrate surface from being influencedby outside gas.